CHAPTER LXXIX 

 THE THEORY OF EVOLUTION— THE ORIGIN OF SPECIES 



If we admit that the existing Icinds or species of animals 

 have arisen by a process of evolution from pre-existing species, 

 the pertinent question "How?" demands an answer. Our 

 ignorance is here so profound that we have so far only been 

 able to frame working- hypotheses to account for the facts. And 

 every theory from time to time propounded leads to endless 

 controversy, though, on the whole, we are constantly getting 

 nearer to the heart of things. Everything depends upon the 

 properties and possibilities of the living substance (protoplasm) 

 which is the essential part of every organism, but it is precisely 

 here that the gaps in our knowledge are most painfully obvious. 

 The history of every science presents us with regularly alter- 

 nating phases of fact-collection, and generalization upon facts. 

 At the present time we badly need more facts, upon which to 

 base further speculations as to the methods of evolution. And 

 this is more particularly true regarding experiments on heredity 

 and related matters, upon which satisfactory answers to evolu- 

 tionary questions must necessarily depend. 



We are here only concerned with a brief statement of the 

 leading theories and principles which have so far been brought 

 forward, commencing with the doctrine of Natural Selection, 

 simultaneously advanced by Darwin and Wallace, and which has 

 had a quite unprecedented influence upon the methods of human 

 thoug-ht. 



NATURAL SELECTION (DARWINISM) 



& 



This theory of evolution, which is essentially of utilitarian 

 character, marshals together a large number of indisputable facts, 

 suggests their mutual relations, and builds up, step by step, a 

 very convincing hypothesis as to how and why new species have 



